Dialysis, i.e. the separation of materials based on differences in chemical potential through contact with a membrane, has been used to remove dissolved inorganic or organic materials from liquid or gaseous solutions, e.g. the artificial kidney machine. The dissolved materials which pass through the membrane are swept away or otherwise removed from the proximity of the membrane to maintain as high a driving force as possible. However, because of relatively low permeation rates through the membrane, such dialysis processes require a large membrane surface area and/or long contact time to permit effective separation to take place and a large volume of sweep fluid resulting in a relatively dilute sweep stream.
In many instances it would be desirable to separate out the disperse phase in a heterogeneous dispersion such as chemical waste streams (e.g. polysubstituted phenolics in an aqueous dispersion) or stack gases. Phase separation has been used but is limited by the ability to detect the interface. Filtration, or even ultrafiltration, has been used in some cases but is limited to relatively large particle size dispersions.
An object of the present invention is to provide a method for removing a disperse phase from a heterogeneous dispersion.
A further object of the present invention is to provide a method for removing a disperse phase from an aqueous dispersion.
Still another object of the present invention is to provide a method of removing a disperse phase from a heterogeneous dispersion wherein the disperse phase so separated is concentrated, recovered and/or converted to a useful material.
Another object of the present invention is to provide a method of removing and recovering polysubstituted phenolics from aqueous waste streams.